The aim of this project is to study in depth (using a multidisciplinary approach) some fundamental mechanisms responsible for the onset of activity and neuron behavior in sensory systems. Thus, seven independent but closely integrated projects are presented: 1) A study of the functional properties of the basement membrane which is common to nerves, muscles, synaptic and sensory junctions; 2) Basic membrane properties of photoreceptors which will be studied with intracellular techniques, voltage clamping and ion-sensitive photodyes; 3) Studies on the electrical and trophic properties of sensory synapses in carotid body chemoreceptors by using adult synapses and tissue culture; 4) Biochemistry of carotid body sensory synapses with emphasis on content and release of putative neurotransmitters and the enzymatic systems responsible for their synthesis; 5) Neuroanatomy and electrophysiology of the vertebrate retina to study the basic processes of color coding and orientation selectivity at this level. Intracellular recordings, Golgi and HRP staining of recorded cells will be employed; 6) How the sensation of itch is signaled to the CNS and how pruritus can be inhibited. This study will employ recordings from single C afferent fibers from the skin; and 7) An analysis of responses evoked in the somatosensory cortex by skin stimulation before and after regeneration of injured skin nerves. It is hoped to determine whether or not somatotopic localization is altered. The purpose of this group is to establish a better understanding of basic sensory mechanisms both at the receptor and CNS levels. The group has enough cohesion to attain these objectives. In addition, this multidisciplinary approach will be conducted in well equipped laboratories manned by competent investigators, having access to excellent core facilities which include electrophysiological, neuroanatomical, neurochemical, computational and service laboratories.